Generalize AllocationSite field access in HObjectAccess.

There are simply becoming too many individual field accessors, and
more are coming.

R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/43563002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17408 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Cast const char * to const uint8_t *, which removed a unnecessary version of InternalStringToDouble template.

Code size (android arm build for d8):
old d8: 17,479,047 bytes
new d8: 17,445,492 bytes
Total code size saved: 33,555 bytes

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/36903002

Patch from Bangfu Tao <bangfu.tao@samsung.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17409 ce2b1a6d-e550-0410-aec6-3dcde31c8c00